This invention relates to a method of manufacturing a sensor using resistance elements and, more particularly, to a method of manufacturing a sensor for detecting, as changes in electric resistance, a mechanical deformation applied to resistance elements formed on a semiconductor substrate.
As a sensor for force, acceleration, or magnetism, etc., there have been proposed novel sensors in which resistance elements are formed on a semiconductor substrate to allow these resistance elements to produce machanical deformations by force, acceleration or magnetism, etc. applied, thus to detect such mechanical deformations as changes in electric resistance values. For example, in the Official Gazette of the International Laid Open No. WO88/08522 of the International Application based on the Patent Cooperation Treaty, there is disclosed a detector for force, acceleration or magnetism using resistance element which has been invented by the same inventor as the inventor of this application.
For manufacturing such a sensor, an impurity diffusion process, etc. is implemented to a semiconductor wafer to form a large number of resistance elements at respective predetermined positions. Also many chemical or physical processes are implemented to form grooves for rendering flexibility, and to form wiring layers. The semiconductor wafer is then cut into a plurality of semiconductor pellets by a dicing process. Each pellet serves as a main unit of a single independent force sensor. Thereafter, a weight body is connected to a working portion of the pellet in the case of manufacturing an acceleration sensor, and a magnetic body is connected thereto in place of the weight body in the case of manufacturing a magnetic sensor. Finally, this pellet is accommodated into a package and is then subjected to wire bonding. Thus, a chip is completed as a sensor unit.
In the above-described conventional manufacturing method, at the stage for processing a semiconductor wafer, processing can be implemented at the same time to a plurality of sensor units formed on a single wafer. However, after the wafer is cut off by a dicing process, it is required to separately process respective units. For example, weight bodies are required to be connected to every unit in the case of the acceleration sensor, and magnetic bodies are required to be connected to every unit in the case of the magnetic sensor. In addition to the above, pedestals for supporting respective pellets must be connected every unit. Further, it is also required to connect, every unit, control members for allowing the weight body or the magnetic body not to move exceeding an allowed range in order to prevent the semiconductor substrate from being mechanically broken when a large force is applied to the weight body or the magnetic body. As stated above, the conventional manufacturing method has many process steps which should be processed on every pellet, resulting in a poor efficiency and a lowered productivity. Namely, the conventional method has the problem that it is not suitable for mass production, resulting in an increased cost of products.